Electrical Properties Of TiO2 Films Research Articles

Electrical properties of TiO2 films synthetized by sol-gel process

Titanium oxide (TiO2) is one of the most used metal oxides for its multiple applications due to its high sensitivity, fast response, low cost, no toxicity and used in hostile environments. In this work was deposited TiO2 film on 304 stainless steel substrates using the spin coating technique. The synthesis of the deposited solution was with the sol-gel method a temperature environment, obtained TiO2 films on different thermal treatments. The results of the experiment show film: with a thickness from 0.6 to 1μm, anatase phase at the plane (101). The Raman spectroscopy confirms the TiO2 anatase phase. The resistivity decreases, and conductivity increases with increasing temperature. The micrograph SEM observes a compact and smooth homogeneous surface with an average size of 18.40nm to 7nm.

The Effect of Solvent Variation on Structural, Optical, and Electrical Properties of TiO2 Films Prepared by Hydrothermal Method

The Effect of Solvent Variation on Structural, Optical, and Electrical Properties of TiO2 Films Prepared by Hydrothermal Method

Impact of the Growth Mechanisms on Si and Glass Substrates on the Structural, Optical and Electrical Properties of Anatase TiO2 Thin Films Synthetized By ALD Technique (Oral)

Titanium dioxide is a multipurpose material leading to many applications such as Li ion batteries, photocatalysis, dielectric in capacitors or transparent conductive oxides 1–3. Indeed, TiO2 can be stabilized under different crystallographic structures and the possibility to tune the oxygen stoichiometry offers a large range of electronic properties 1. Furthermore, among all allotropic forms of TiO2, the crystalline anatase phase is particularly interesting in optoelectronics and photocatalysis because of its long exciton lifetime and its semiconductor behaviour with a wide indirect bandgap of 3.2 eV 2. Depending on the application purpose, we will show the possibility to deposit anatase TiO2 films on single crystalline silicon substrates for microelectronics applications and on transparent glass substrates for photoelectrochemical cells or for TiO2-based TCOs materials, which require high transparency in the visible range. For both substrates, the growth mechanism of TiO2 is required to be understood and its impact on the optical end dielectric properties.TiO2 films were grown by atomic layer deposition (ALD) on (100) oriented p-type silicon and Schott glass substrates in a low deposition temperature (TD) range from 100°C to 300°C with titanium tri-isopropoxide (TTIP) precursor and water as oxidizing agent. A structural (TEM, XRD, AFM, Raman and FTIR), optical (ellipsometry, UV-vis-NIR spectroscopy) and electrical study was carried out.As-deposited TiO2 films were successfully crystallized on both silicon and glass substrates at temperatures ≥ 250°C without post-annealing treatment. All characterizations show that the crystallization on silicon and glass substrates is promoted by the TD increase but also depends of the film thickness. Specifically, it has been found that the growth mechanism follows the one observed elsewhere 4: (i) TiO2 growth begins as amorphous, then after a certain thickness, (ii) crystalline nuclei form randomly at the surface. (iii) These germs grow isotropically through the crystallization of the already deposited surrounding amorphous TiO2, as well as the newly deposited matter.Optical properties such as refractive index, absorption coefficient and band gap were simulated with new amorphous and Tauc-Lorentz dispersion models from ellipsometric measurement on silicon and UV-vis-NIR spectroscopy transmission measurement on glass. Results from both methods are in adequacy, showing an increase of the refractive index and the absorption coefficient with TD. These results are consistent with the densification and crystallization of the material characterized by the structural analysis. Finally, a decrease of the band gap is also observed with the increase of TD which tends to 3.2 eV confirming the formation of the anatase phase 2.For the dielectric properties, the relative permittivity ε’ and the loss angle tan δ of TiO2 films were studied with frequency. The relative permittivity increases with TD, due to the higher crystalline quality of the films. Low losses are observed, indicating a low density of charged defects in the films and a good quality of the dielectric properties.All observed structural, optical and electrical properties of TiO2 films are consistent, showing the possibility to stabilize the wide band gap anatase TiO2 on different substrates by ALD at low temperature. This work paves the way for the integration of this extremely versatile oxide for future devices.(1) Elbahri, M. B.; Kahouli, A.; Mercey, B.; Prellier, W.; Lüders, U. Effects of Oxygen Pressure during Deposition on the Dielectric Properties of Amorphous Titanium Dioxide Thin Films. J. Phys. Appl. Phys. 2019, 52 (17), 175308. https://doi.org/10.1088/1361-6463/ab06a1.(2) Niemelä, J.-P.; Marin, G.; Karppinen, M. Titanium Dioxide Thin Films by Atomic Layer Deposition: A Review. Semicond. Sci. Technol. 2017, 32 (9), 093005. https://doi.org/10.1088/1361-6641/aa78ce.(3) Mo, S.-D.; Ching, W. Y. Electronic and Optical Properties of Three Phases of Titanium Dioxide: Rutile, Anatase, and Brookite. Phys. Rev. B 1995, 51 (19), 13023–13032. https://doi.org/10.1103/PhysRevB.51.13023.(4) Puurunen, R. L.; Sajavaara, T.; Santala, E.; Miikkulainen, V.; Saukkonen, T.; Laitinen, M.; Leskelä, M. Controlling the Crystallinity and Roughness of Atomic Layer Deposited Titanium Dioxide Films. J. Nanosci. Nanotechnol. 2011, 11 (9), 8101–8107. https://doi.org/10.1166/jnn.2011.5060.

A study of the effect of morphology on the optical and electrical properties of TiO2 nanotubes for gas sensing applications

In this paper, we report the results of the optical and electrical properties of TiO2 nanotubes with different morphologies for gas sensing applications. Four nanomaterials of TiO2 were prepared by electrochemical anodization using four different electrolyte solutions: 0.255 wt% NH4F with 1 wt%, 3 wt%, 6 wt% and 9 wt% of deionized water in ethylene glycol. Micrographs by scanning electron microscopy (SEM) showed different morphologies caused by the variation in the water content of the solutions. Consequently, as an effect of morphology, the photoluminescence intensity in the visible spectrum was modified. By a change of the crystalline phase of TiO2 nanotubes, the oxygen vacancies increased and affected to the optical and electrical properties of TiO2 films. These films were used for detecting gas at room temperature. Hence, we studied and analyzed the relationship of the morphology, elemental composition, phase composition, band gap energy and defect states as a function of the electrical resistance change of TiO2 nanotubes to understand and improve the sensor response.

Study of micro-structural, optical and electrical properties of TiO2 films obtained from micro-controller based SILAR method

The TiO2 films were obtained from successive ion layer adsorption and reaction (SILAR) method. A micro-controller based SILAR unit was used to precisely monitor and control the deposition parameters. The films were uniform and free from physical defects such as pores and cracks. A maximum thickness of about 700 nm was achieved. The films were found to be polycrystalline without any texture or preferred orientations. The crystallite size of the films was found to increase with thickness while the micro strain and stress were found to reduce with the thickness. Post-deposition annealing was also found to produce the similar results. The films were found to possess an indirect bandgap of about 3 eV. Various technically important parameters such as root-mean-square micro strain, Urbach energy, chemical composition, carrier concentration, electrical resistivity etc. were determined. The effects of deposition parameters on the properties of the films is discussed in detail.

Effect of Sn doping on the structural, optical and electrical properties of TiO2 films prepared by spray pyrolysis

In this work, highly oriented pure and Tin-doped Titanium dioxide (Sn-doped TiO2) with porous nature photoelectrodes were deposited on ITO glass plates using spray pyrolysis technique. The XRD pattern revealed the formation of anatase TiO2 with the maximum intensity of (101) plane while doping 6at% of Sn. The morphological studies depicted the porous nature with the uniform arrangement of small-sized grains. The presence of tin confirmed with the EDX spectra. The size of particles of 13nm was observed from High Resolution Transmission Electron Microscopy (HR-TEM) analysis. The average transmittance was about 85% for the doped photoelectrode and was observed for the photoelectrode deposited with 6at% of tin, with decreased energy band gap. The PL study showed the emission peak at 391 nm. The maximum carrier concentration and Hall mobility was observed for the photoelectrode deposited with 6at% of tin. With these studies, the DSSCs were prepared separately with the dye extracted from Hibiscus Rosasinesis and Hibiscus Surttasinesis and their efficiency was maximum for the DSSC prepared with 6at% of tin.

Effect of Sn doping on the structural, optical and electrical properties of TiO2 films prepared by spray pyrolysis

In this work, highly oriented pure and tin-doped titanium dioxide (Sn-doped TiO2) with porous nature photoelectrodes were deposited on ITO glass plates using spray pyrolysis technique. The XRD pattern revealed the formation of anatase TiO2 with the maximum intensity of (101) plane while doping 6 at.% of Sn. The morphological studies depicted the porous nature with the uniform arrangement of small-sized grains. The presence of tin confirmed with the EDX spectra. The size of particles of 13 nm was observed from high resolution transmission electron microscopy analysis. The average transmittance was about 85 % for the doped photoelectrode and was observed for the photoelectrode deposited with 6 at.% of tin with decrease in the energy band gap. The PL study showed the emission peak at 391 nm. The maximum carrier concentration and Hall mobility was observed for the photoelectrode deposited with 6 at.% of tin. With these studies, the DSSCs were prepared separately with the dye extracted from Hibiscus rosasinesis and Hibiscus surattensis and their efficiency was maximum for the DSSC prepared with 6 at.% of tin.

Properties of TiO2 films on silicon substrate

Influence of the substrate material and the effect of oxygen plasma on the microprofile and electrical properties of TiO2 films deposited by radio-frequency magnetron sputtering are studied. It is shown that the most continuous films with the smallest roughness are obtained when deposited onto silicon substrates. The change in the capacitance-voltage and conductance-voltage characteristics of the structures upon their exposure to oxygen plasma is accounted for by the diffusion of oxygen atoms across the titanium-dioxide film and by the appearance of a SiO2 layer at the Si-TiO2 interface.

Capacitance-voltage analysis of a high-k dielectric on silicon

Device characteristics of TiO2 gate dielectrics deposited by a sol-gel method and DC sputtering method on a P-type silicon wafer are reported. Metal—oxide—semiconductor capacitors with Al as the top electrode were fabricated to study the electrical properties of TiO2 films. The films were physically characterized by using X-ray diffraction, a capacitor voltage measurement, scanning electron microscopy, and by spectroscopy ellipsometry. The XRD and DST-TG indicate the presence of an anatase TiO2 phase in the film. Films deposited at higher temperatures showed better crystallinity. The dielectric constant calculated using the capacitance voltage measurement was found to be 18 and 73 for sputtering and sol—gel samples respectively. The refractive indices of the films were found to be 2.16 for sputtering and 2.42 for sol—gel samples.

Effects of annealing on the electrical properties of TiO2 films deposited on Ge-rich SiGe substrates

Titanium oxide (TiO2) high-k dielectric layers were deposited on the Si0.3Ge0.7 substrates by plasma enhanced chemical vapor deposition (PECVD) at low temperature (150°C). To study the effects of annealing on the electrical properties, the TiO2 films were annealed in pure nitrogen ambient in the temperature range of 400–600°C. Good electrical performance for the gate dielectrics was observed for the dielectric films annealed up to 500°C, in terms of interface state density, leakage current, and charge trapping properties. Annealing at 600°C is found to degrade the electrical properties due to Ge segregation and subsequent diffusion into the TiO2 layer. Schottky emission was found to be the dominant leakage current conduction mechanism in PECVD TiO2 films.

A comparative study of the electrical properties of TiO2 films grown by high-pressure reactive sputtering and atomic layer deposition

Oxide–semiconductor interface quality of high-pressure reactive sputtered (HPRS) TiO2 films annealed in O2 at temperatures ranging from 600 to 900 °C, and atomic layer deposited (ALD) TiO2 films grown at 225 or 275 °C from TiCl4 or Ti(OC2H5)4, and annealed at 750 °C in O2, has been studied on silicon substrates. Our attention has been focused on the interfacial state and disordered-induced gap state densities. From our results, HPRS films annealed at 900 °C in oxygen atmosphere exhibit the best characteristics, with Dit density being the lowest value measured in this work (5–6 × 1011 cm−2 eV−1), and undetectable conductance transients within our experimental limits. This result can be due to two contributions: the increase of the SiO2 film thickness and the crystallinity, since in the films annealed at 900 °C rutile is the dominant crystalline phase, as revealed by transmission electron microscopy and infrared spectroscopy. In the case of annealing in the range of 600–800 °C, anatase and rutile phases coexist. Disorder-induced gap state (DIGS) density is greater for 700 °C annealed HPRS films than for 750 °C annealed ALD TiO2 films, whereas 800 °C annealing offers DIGS density values similar to ALD cases. For ALD films, the studies clearly reveal the dependence of trap densities on the chemical route used.

Electrical properties of TiO2 films deposited on strained Si1−yCy layers

Insulating high dielectric constant (high-k) titanium dioxide (TiO2) films have been deposited on solid phase epitaxially-grown tensilely strained Si1−yCy layers by microwave plasma enhanced chemical vapour deposition using titanium tetrakis isopropoxide (TTIP) as source material and oxygen. Using metal insulator semiconductor capacitor structure, the interface and electrical properties have been studied both at room and high temperature. Good electrical properties are observed in deposited TiO2 thin films.

Effect of rapid thermal annealing on the structural and electrical properties of TiO2 thin films prepared by plasma enhanced CVD

Titanium oxide thin films were deposited on p-type Si(100), SiO2/Si, and Pt/Si substrates by plasma enhanced chemical vapor deposition using high purity Ti(O-i-C3H7)4 and oxygen. As-deposited amorphous TiO2 thin films were treated by rapid thermal annealing (RTA) in oxygen ambient, and the effects of RTA conditions on the structural and electrical properties of TiO2 films were studied in terms of crystallinity, microstructure, current leakage, and dielectric constant. The dominant crystalline structures after 600 and 800 ‡C annealing were an anatase phase for the TiO2 film on SiO2/Si and a rutile phase for the film on a Pt/Si substrate. The dielectric constant of the as-grown and annealed TiO2 thin films increased depending on the substrate in the order of Si, SiO2/Si, and Pt/ Si. The SiO2 thin layer was effective in preventing the formation of titanium silicide at the interface and current leakage of the film. TEM photographs showed an additional growth of SiOx from oxygen supplied from both SiO2 and TiO2 films when the films were annealed at 1000 ‡C in an oxygen ambient. Intensity analysis of Raman peaks also indicated that optimizing the oxygen concentration and the annealing time is critical for growing a TiO2 film having high dielectric and low current leakage characteristics.

Electrical properties of TiO2 films deposited by a reactive-ionized cluster beam

Titanium dioxide films of 100–450-nm thickness were deposited on fused quartz and silicon substrates heated at 350 °C by a reactive-ionized cluster-beam deposition. After the deposition, films were annealed at 600 °C in dry O2 ambient. The electrical properties of TiO2 films and the TiO2-Si interface were analyzed. The dielectric constant of the film after the annealing was in a range of 35–108, which depended on the deposition conditions. The films showed a high breakdown voltage and a sufficiently low interface-state density of 1–2×1011 cm−2 eV−1 at the midgap.

ChemInform Abstract: Effects of Small Amount of Water on Physical and Electrical Properties of TiO2 Films Deposited by CVD Method.

AbstractIt is shown that physical properties of TiO2 such as refractive index, etching rate, and dielectric constant are dependent on the amount of water added in the CVD process, revealing that precise control of the amount of water added to the sources is very important to obtain reproducible products.

Effects of Small Amount of Water on Physical and Electrical Properties of TiO2 Films Deposited by CVD Method

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